1. Field of the Invention
The present invention relates to an electric bending endoscope apparatus having an electric bending endoscope.
2. Description of the Related Art
Recently, an endoscope is widely used for various curing treatments which are performed by inserting an elongated inserting portion in the celom so as to observe the organ in the celom or by using a treatment tool inserted through a processing tool channel as needed.
The endoscope generally has a bending portion which is bent vertically or horizontally, or vertically and horizontally at a distal portion of the inserting portion. The bending portion is bent in a desired direction by stretching and contracting a bending wire which is inserted in the inserting portion.
In general, the bending wire is stretched or contracted by a bending knob manually. However, the endoscope recently includes an electric bending endoscope which is stretched by bending motive means such as an electric motor. In the electric bending endoscope, the bending portion is bent by operating, for example, bending operation instructing means such as a joystick arranged to an operating portion. In other words, the electric motor is rotated by a predetermined amount based on an operation instructing signal from the bending operation instructing means. Then, the rotation of the electric motor is transmitted to a pulley, the bending wire wound to the pulley is stretched, and the bending portion is bent. In the above-mentioned electric bending endoscope, the bending portion is easily and desirably bent by a single finger. Accordingly, the operability is improved because another finger operates another switch arranged to the operating portion.
However, in the electric bending endoscope, the bending wire is always under tension irrespective of in a bending status or non-bending status. Then, the following is requested to the electric bending endoscope.
(1) Since the bending wire is always under tension, the tension causes the stretch of the bending wire. In order to prevent the stretch of the bending wire, unnecessary tension should be prevented upon cleaning, storing, and carrying.
(2) When the tension is always placed, external force to the inserting portion during the inserting operation does not change the bending status of the bending portion. Thus, the tension is not placed to the bending wire and, in this status, a freely bending status is requested. In this status, the bending status of the bending portion freely changes in accordance with the external force acted on the inserting portion, namely, the bending portion is freely bent and changed.
(3) When a default is caused during the inserting operation or when a failure is caused in examination, it is requested that the freely bending status is obtained and the inserting portion is removed from the celom.
Endoscopes to respond to the above requests are proposed. For example, an electric bending endoscope has means for restoring transmission and disconnection of driving force which can switch a disconnecting status/connecting status of the tension acting on the bending wire in accordance with the necessity. Further, Japanese Unexamined Patent Application Publication No. 6-269398 discloses an endoscope which surely switches a locking status and a free status of the bending portion by arranging switching means which can switch a stretching status and a contracting status of a stretching member.
Furthermore, an electric bending endoscope includes the means for restoring the transmission and disconnection of the driving force and bending operation instructing means in which a track ball for instructing the bending operation of the bending portion as the change in relative position is arranged to the operating portion. In the electric bending endoscope having the track ball, the bending status of the bending portion is relatively changed in the operating direction by operating tracking ball, the stop of the operation of the track ball enables a re-operation waiting status, and the stop point becomes a re-operation start point.